In a conventional punch press, when a plate-like work is punched out using a punch and a die, it is known that a punching rises together with the punch (slug rising) when the punch rises. In a state where the punching rises to an upper surface of a work, if a punching working or operation of a next work is carried out successively, the punching operation of the work may be carried out while the punching is interposed between the works in some cases, and the punch may be damaged.
In order to prevent the punching from rising, a die hole of the die is contrived variously, or the punching is drawn from below the die. For example, Japanese Utility Model Application Publication No. S52-50475 discloses a technique for drawing the punching downward.
In a first conventional technique, a die is mounted on an upper surface of a die holder, the die holder is provided with a discharge hole through while punching punched out by the die is dropped, and an air hole from which air is injected is inclined and provided in the discharge hole such that the air hole is directed downward. Air is injected downwardly from the air hole into the discharge hole, thereby sucking air from above the discharge hole.
In this structure, there are problems that it is difficult to form the air hole, a distance from the air hole to the die hole of the die is long, and the sucking effect is not sufficient.
Other than the first conventional technique, there are second and third conventional techniques disclosed in Japanese Patent Publication No. 3245935 and Japanese Patent Application Laid-Open No. Hei-5-57687.
In structures of the second and the third conventional techniques, an air injection hole is inclined from a peripheral surface of a cylindrical die to a discharge hole. If the air injection hole is expressed in a sectional view of an end surface taken along an axis of the die at an outer peripheral surface of the die, the air injection hole is worked from a portion expressed as a straight line which is in parallel to the axis of the die. Therefore, the conventional technique has a problem that it is troublesome to work the air injection hole, and the structure becomes expensive. When the air injection hole is deep, there are problems that a thin and long drill is required, and when the working of the air injection hole is started, a tip end of the drill is prone to deviate from the working position, the drill is prone to be bent and damaged.
The present invention has been achieved in order to solve the above problems, and it is an object of the present invention to provide a die and a die apparatus that can prevent a punching from rising.